Adhesives are widely used for securing a variety of articles to substrates. Pressure sensitive adhesives (PSA) are well known and are used for a variety of industrial, consumer, and medical applications. Pressure sensitive adhesives are characterized as being normally tacky and exhibiting instant tack when applied to a substrate. A variety of polymers have been used to manufacture pressure sensitive adhesives, for example, acrylic and methacrylic ester homo- or copolymers, butyl rubber-based systems, silicones, nitriles, styrene block copolymers, ethylene-vinyl acetate, urethanes, vinyl esters and amides, olefin copolymer materials, natural or synthetic rubbers, and the like.
Pressure sensitive adhesives have been widely studied in an attempt to tailor their properties so that they readily debond from a given substrate. It is especially desirable for skin-contact adhesives, such as those used in wound dressings, to have very high initial adhesion. This enables them to be easily applied, remain securely attached in place, and act as good barriers against external microbial contaminants. At the same time, it is preferred that the adhesive be easy to remove. Tissue trauma resulting from removal of adhesive articles is a well-documented phenomenon that can delay wound healing, increase wound size, and cause significant pain.
There are numerous strategies for mitigating the trauma associated with removing skin adhesives. Some strategies employ a debonding agent to the article that reacts with the adhesive causing a loss of adhesion. Other strategies deactivate the adhesive on demand by using an external trigger, such as temperature changes, light exposure, hydration, or the like. Other strategies simply rely on striking a compromise between adhesive strength and ease of removal, soft silicone adhesives being an excellent example. These efforts have often led to less than optimum results. The problems include unsatisfactory reduction in bonding strength or the dissolution of the pressure sensitive adhesive in the debonding agent. When the pressure sensitive adhesive dissolves, it can leave a tacky residue on the substrate subsequent to removal.
While prior efforts have been undertaken to incorporate microparticles or microcapsules in a pressure sensitive adhesive, such efforts have had limitations and problems. Various types of microparticles and microcapsules have included blowing agents, water soluble tackifiers, or hydrocolloid particles. These strategies have led to two problems: 1) a significant decrease in the initial bonding strength of the adhesive; and 2) a need to use an undesirable debonding agent such as heat, ultraviolet light, or acidic or basic solutions.
Pressure sensitive adhesives have been incorporated into a wide variety of products including those used in medical applications, automobile applications, and adhesive tapes. While many commercial products are known to facilitate removing an adhesive article from a substrate, there remains a need to utilize a selective debonding agent to facilitate the removal of such articles.